Richard Biener <richard.guent...@gmail.com> writes:
> On Fri, Nov 29, 2019 at 11:53 AM Richard Sandiford
> <richard.sandif...@arm.com> wrote:
>>
>> When dissolving an SLP-only group of accesses, we should only set
>> the gap to group_size - 1 for normal non-strided groups.
>>
>> Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
>
> OK. Probably also broken on branch(es).
It looks like it's trunk only -- we didn't dissolve DR groups here
until the support for SLP masked loads (r271704).
Thanks,
Richard
>
> Richard.
>
>> Richard
>>
>>
>> 2019-11-29 Richard Sandiford <richard.sandif...@arm.com>
>>
>> gcc/
>> PR tree-optimization/92677
>> * tree-vect-loop.c (vect_dissolve_slp_only_groups): Set the gap
>> to zero when dissolving a group of strided accesses.
>>
>> gcc/testsuite/
>> PR tree-optimization/92677
>> * gcc.dg/vect/pr92677.c: New test.
>>
>> Index: gcc/tree-vect-loop.c
>> ===================================================================
>> --- gcc/tree-vect-loop.c 2019-11-29 09:13:43.764143091 +0000
>> +++ gcc/tree-vect-loop.c 2019-11-29 10:52:30.475476141 +0000
>> @@ -1829,7 +1829,10 @@ vect_dissolve_slp_only_groups (loop_vec_
>> DR_GROUP_FIRST_ELEMENT (vinfo) = vinfo;
>> DR_GROUP_NEXT_ELEMENT (vinfo) = NULL;
>> DR_GROUP_SIZE (vinfo) = 1;
>> - DR_GROUP_GAP (vinfo) = group_size - 1;
>> + if (STMT_VINFO_STRIDED_P (first_element))
>> + DR_GROUP_GAP (vinfo) = 0;
>> + else
>> + DR_GROUP_GAP (vinfo) = group_size - 1;
>> vinfo = next;
>> }
>> }
>> Index: gcc/testsuite/gcc.dg/vect/pr92677.c
>> ===================================================================
>> --- /dev/null 2019-09-17 11:41:18.176664108 +0100
>> +++ gcc/testsuite/gcc.dg/vect/pr92677.c 2019-11-29 10:52:30.475476141 +0000
>> @@ -0,0 +1,26 @@
>> +/* { dg-do compile } */
>> +/* { dg-additional-options "-O3" } */
>> +
>> +int a, c;
>> +int *b;
>> +long d;
>> +double *e;
>> +
>> +void fn1() {
>> + long f;
>> + double g, h;
>> + while (c) {
>> + if (d) {
>> + g = *e;
>> + *(b + 4) = g;
>> + }
>> + if (f) {
>> + h = *(e + 2);
>> + *(b + 6) = h;
>> + }
>> + e += a;
>> + b += 8;
>> + c--;
>> + d += 2;
>> + }
>> +}
